Toxicity to aquatic algae and cyanobacteria.006 to 007

Toxicity to aquatic algae and cyanobacteria.006

Administrative data

Purpose flag:

supporting study

Study result type:

read-across from supporting substance (structural analogue or surrogate)

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

No guideline or GLP compliance stated

Data source

Reference

Reference Type:

publication

Title:

Toxicity of chlorate and chlorite to selected species of algae, bacteria, and fungi.

Author:

van Wijk DJ, Kroon SGM & Garttener-Arends ICM.

Bibliographic source:

Ecotoxicology and Environmental Safety 40: 206-211

Materials and methods

Test materials

Identity of test material same as for substance defined in section 1 (if not read-across):

no

Test material identityopen allclose all

Test material identity 1

Identifier:

CAS number

Identity:

7758-19-2

Test material identity 2

Identifier:

EC number

Identity:

231-836-6

Test material identity 3

Identifier:

IUPAC name

Identity:

sodium chlorite

Details on test material:

Tests performed with chlorite

Test organisms

Test organisms (species):

other: Selenastrum capricornutum, Ectocarpus variabilis and Nostoc calcicola

Results and discussion

Effect concentrationsopen allclose all

Effect concentrations 1

Duration:

14 d

Endpoint:

LOEC

Effect conc.:

2.98 other: mM

Remarks (e.g. 95% CL):

Ectocarpus variabilis. Nitrogen source: Nitrate

Effect concentrations 2

Duration:

14 d

Endpoint:

NOEC

Effect conc.:

0.99 other: mM

Remarks (e.g. 95% CL):

Ectocarpus variabilis. Nitrogen source: Nitrate

Effect concentrations 3

Duration:

96 h

Endpoint:

EC50

Effect conc.:

0.01 other: mM

Remarks (e.g. 95% CL):

Selenastrum capricornutum. Nitrogen source: Nitrate

Effect concentrations 4

Duration:

96 h

Endpoint:

EC50

Effect conc.:

0.06 other: mM

Remarks (e.g. 95% CL):

Nitrogen source: Ammonium

Effect concentrations 5

Duration:

96 h

Endpoint:

LOEC

Effect conc.:

0.001 other: mM

Remarks (e.g. 95% CL):

Selenastrum capricornutum. Nitrogen source: Nitrate

Effect concentrations 6

Duration:

96 h

Endpoint:

LOEC

Effect conc.:

0.011 other: mM

Remarks (e.g. 95% CL):

Nitrogen source: Ammonium

Effect concentrations 7

Duration:

96 h

Endpoint:

NOEC

Effect conc.:

< 0.001 other: mM

Remarks (e.g. 95% CL):

Selenastrum capricornutum. Nitrogen source: Nitrate

Effect concentrations 8

Duration:

96 h

Endpoint:

NOEC

Effect conc.:

0.001 other: mM

Remarks (e.g. 95% CL):

Nitrogen source: Ammonium

Effect concentrations 9

Duration:

14 d

Endpoint:

EC50

Effect conc.:

0.06 other: mM

Remarks (e.g. 95% CL):

Nostoc calcicola. Nitrogen source: Nitrate

Effect concentrations 10

Duration:

14 d

Endpoint:

EC50

Effect conc.:

0.07 other: mM

Remarks (e.g. 95% CL):

Nitrogen source: Ammonium

Effect concentrations 11

Duration:

14 d

Endpoint:

LOEC

Effect conc.:

0.02 other: mM

Remarks (e.g. 95% CL):

Nostoc calcicola Nitrogen source: Nitrate

Effect concentrations 12

Duration:

14 d

Endpoint:

LOEC

Effect conc.:

0.02 other: mM

Remarks (e.g. 95% CL):

Nitrogen souorce: Ammonium

Effect concentrations 13

Duration:

14 d

Endpoint:

NOEC

Effect conc.:

< 0.02 other: mM

Remarks (e.g. 95% CL):

Nostoc calcicola. Nitrogen source: Nitrate

Effect concentrations 14

Duration:

14 d

Endpoint:

NOEC

Effect conc.:

< 0.01 other: mM

Remarks (e.g. 95% CL):

Nitrogen source: Ammonium

Any other information on results incl. tables:

No other informations

Applicant's summary and conclusion

Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignme

Toxicity to aquatic algae and cyanobacteria-007

Administrative data

Purpose flag:

key study

Study result type:

read-across from supporting substance (structural analogue or surrogate)

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

GLP study according to the guideline

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report Date:

2008

Materials and methods

Test guideline

Qualifier:

according to

Guideline:

ISO 10253 (Water quality - Marine Algal Growth Inhibition Test with Skeletonema costatum and Phaeodactylum tricornutum)

Deviations:

yes

Remarks:

The actual test temperature was 23.1 to 23.7 °C

GLP compliance:

yes (incl. certificate)

Remarks:

except for the chemical analyses the study was performed under GLP

Test materials

Identity of test material same as for substance defined in section 1 (if not read-across):

no

Test material identityopen allclose all

Test material identity 1

Identifier:

CAS number

Identity:

7758-19-2

Test material identity 2

Identifier:

EC number

Identity:

231-836-6

Details on test material:

- Lot no.: 1358025
- Purity: 80.6 %
- Impurities: moisture < 1.25%, alkali (as Na2CO3) ~4%, the remainder mainly NaCl (10-13%)
- Appearance: White powder
- Storage until required: at room temperature away from light

Analytical monitoring:

yes

Details on sampling:

Samples were taken at the beginning and end of the test.
Test samples of about 10 mL were taken from each test vessel. The replicate concentration samples were pooled and 10 mL of this solution was filtered using a Pall 0.45 µm GHP Acrodisc filter to remove the algae. Samplese were stored in the refridgerator together with control standards.
Before analysis with IC/MS under the conditions described above the samples were diluted 10 times with de-ionised water.

Vehicle:

no

Details on test solutions:

Preparation of the stock solutions
The test substance is soluble in water. The test substance stock solution of 10.02 g/L was prepared by loading an accurately measured amount of 2.0046 g of test substance, weighed out on an analytical balance in 200 mL of deionized water. The stock solution was mechanically stirred for approx. 30 minutes until a homogenous solution was obtained. A diluted stock solution of 1.00 g/l was prepared by pipetting 9.98 mL into a 100 mL measuring flask and fill it up to the mark with deionized water.
Clear solutions were obtained.

Preparation of the test solutions
The test solutions were prepared by addition of the adequate amounts of stock solution to the test vessels, then test medium was added up to the required final volume. The stock solution of 10 g/L was used to prepare the two highest test concentrations and the diluted stock of 1 g/L was used for preparation of the lower test concentrations. The dilution factor of the test medium by adding the stock solution was never more than 2.5%

Test organisms

Test organisms (species):

Phaeodactylum tricornutum

Details on test organisms:

The test was carried out with the marine alga Phaeodactylum tricornutum CCAP 1052/1A obtained from the Culture Collection of Algae and Protozoa, Dunstaffnage Marine Laboratory, Oban, United Kingdom. After purchasing this strain was cultured and maintained. Cultures on sloped agar tubes were stored at 4°C until required.

Study design

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Test temperature:

23.1 to 23.7 °C

pH:

7.9-8.5

Salinity:

22 g/L NaCl

Nominal and measured concentrations:

Nominal: control, 2.56, 6.4, 16, 40 and 100 mg/L
Measured: < LOD, 3.0, 5.9, 13.9, 37.9, 99.4 mg/L

The measured concentrations were within 80 to 120% of the nominals, therefore nominal concentrations were used to clculate the effects.

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL Erlenmeyers closed with a cotton-wool stoppers
- Aeration: No
- Initial cells density: 1x10E4 cells/mL
- Control end cells density: 5.25x10E5 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6


GROWTH MEDIUM
- Standard medium used: yes, ISO medium


TEST MEDIUM / WATER PARAMETERS
- Culture medium different from test medium: No


OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: No
- Photoperiod: continuous light
- Light intensity and quality: 94 µmol/m2/s and 98 µmol/m2/s at the beginning and end, respectively
- Salinity (for marine algae): 22 g/L NaCl


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: [counting chamber; electronic particle counter; fluorimeter; spectrophotometer; colorimeter]
- Chlorophyll measurement:
- Other:


TEST CONCENTRATIONS
- Spacing factor for test concentrations:
- Justification for using less concentrations than requested by guideline:
- Range finding study
- Test concentrations:
- Results used to determine the conditions for the definitive study:

Reference substance (positive control):

yes

Remarks:

Potassium chromate

Results and discussion

Effect concentrationsopen allclose all

Effect concentrations 1

Duration:

72 h

Endpoint:

NOEC

Effect conc.:

6.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Endpoint:

LOEC

Effect conc.:

16 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Endpoint:

EC10

Effect conc.:

13.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Endpoint:

EC50

Effect conc.:

19.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 5

Duration:

72 h

Endpoint:

NOEC

Effect conc.:

3.84 other: mg chlorite/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks (e.g. 95% CL):

The result has also been purity corrected

Effect concentrations 6

Duration:

72 h

Endpoint:

EC50

Effect conc.:

11.8 other: mg chlorite/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks (e.g. 95% CL):

The result has also been purity corrected

Details on results:

During the test a Brown-yellow colour was observed in the highest test concentration. This is shown in the absorbances measured, but did not have an impact on the outcome of the test because 100% growth inhibition was seen in 40 mg/L already.

Results with reference substance (positive control):

The sensitivity of the algae was checked by performing a growth inhibition test with a reference compound (potassium dichromate) twice a year, when the cultures are grafted from the sloped agar tubes. The sensitivity was tested for compliance with the Guidelines, which means that the EC50 values are between 14.8-25.4 mg/L.

Reported statistics and error estimates:

Where possible, the EC10,20,50,80 values were computed from the best fitted line (least-squares method) through the points given by the probit of the percentage of inhibition and the logarithm of the concentration of the test substance. The Lowest Observed Effect Concentration (LOEC) was determined by comparison of the growth at each concentration and the control using threshold values from the William’s test. The No Observed Effect Concentration (NOEC) was derived from the results as the first concentration below the LOEC value, where growth shows no significant inhibition relative to the control values. Confidence limits were computed on the basis of Fieller’s theorem if possible. All computations were performed using the TOXCALC version 5.0 program.

Any other information on results incl. tables:

Table 1 Absorbances measured in the algal growth inhibition test with Sodium chlorate

Concentration				Time (hours)
(mg/L)		0		24		48		72
0.000		0.005		0.020		0.079		0.285
0.000		0.005		0.022		0.080		0.271
0.000		0.005		0.022		0.079		0.261
0.000		0.006		0.022		0.077		0.273
0.000		0.005		0.021		0.084		0.281
0.000		0.005		0.022		0.078		0.273
Mean		0.005		0.022		0.080		0.274
2.56		0.005		0.021		0.075		0.256
2.56		0.005		0.023		0.077		0.245
2.56		0.004		0.023		0.083		0.265
Mean		0.005		0.022		0.078		0.255
6.4		0.005		0.022		0.073		0.272
6.4		0.005		0.020		0.067		0.231
6.4		0.005		0.020		0.068		0.239
Mean		0.005		0.021		0.069		0.247
16		0.005		0.018		0.039		0.122
16		0.005		0.018		0.030		0.102
16		0.005		0.020		0.031		0.125
Mean		0.005		0.019		0.033		0.116
40		0.005		0.016		0.005		0.003
40		0.005		0.017		0.006		0.008
40		0.005		0.017		0.006		0.004
Mean		0.005		0.017		0.006		0.005
100*		0.006		0.017		0.017		0.016
100*		0.006		0.015		0.023		0.017
100*		0.005		0.017		0.015		0.013
Mean		0.006		0.016		0.018		0.015

* Increase in absorbances measured is due to the brown-yellow colour

Applicant's summary and conclusion

Conclusions:

The toxicity of Sodium chlorite to an exponentially growing culture of Phaeodactylum tricornutum CCAP 1052/1A was determined over an exposure period of 72 hours.
No significant effects were seen in the two lowest concentrations, therefore NOEC based on growth rate is 6.4 mg/L. The ErC10 is 13.3 mg/L. The ErC50 is 19.6 mg/L.
The test was conducted in a mineral salts medium in acclimatized illuminated orbital incubator. The maximum variation in pH was 0.6 units. 

Executive summary:

In order to predict effects of chemicals in an aquatic environment, the toxicity to marine algae was assessed. The algal toxicity was deter­mined in the Algal Growth Inhibition Test in accordance with ISO test guidelines and with the OECD Principles of Good Laboratory Practice.

The toxicity of Sodium chlorite to an exponentially growing culture of Phaeodactylum tricornutum CCAP 1052/1A was determined over an exposure period of 72 hours.

No significant effects were seen in the two lowest concentrations, therefore NOEC based on growth rate is 6.4 mg/L. The ErC10 is 13.3 mg/L. The ErC50is 19.6 mg/L.

The test was conducted in a mineral salts medium in acclimatized illuminated orbital incubator. The maximum variation in pH was 0.6 units.

The test is valid as shown by:

-    the increase of the absorbance of the control over 72 h by a factor of 53

-    the coefficient of variation of average specific growth rates during the whole test period in the replicate control cultures is 2.1%.

The results of the chemical analyses show that the concentrations in the test solutions at the start and the end of the test are close to the initial nominal concentration. The average measured concentration stayed within 80 to 120% of the nominal and therefore the nominal concentration is used to calculate the effects.

Validity criteria fulfilled:

yes